The bicycle since the year of its initiation which is 1818, has been a vehicle moved by a mechanical system which transmits the muscular force of a person through a pedal towards the sprocket or sprockets of the rear wheel, causing the movement of the vehicle.
The development of the bicycle has been with the relationship between the number of teeth of the wheel, of the pedals and of the sprocket, which can vary between 1:2 and 1:4 by means of a proper change of gears.
Up to now the motive power in bicycles has changed very little. In the racing bicycle, on the toothed crown wheel of the pedal plate, a smaller crown has been coupled in a manner to achieve a greater smoothness in the pedalling. The development of the motive force in a bicycle has been in the relationship between the number of teeth of the crown wheel of the pedal plate, and those of the sprocket of the rear wheel, which can varied between 1:2 and 1:4 turns by means of a proper change of gears, this being the form in general use up to now.
On bicycles now on the market, whether they are geared or not, the command shaft has a sprocket mounted thereon which generally varies only in its diameter size and the number of teeth thereon. A greater diameter gives greater thrust speed; a smaller diameter gives less thrust speed but pedalling is smoother. With respect to the teeth, a greater number of teeth reduces the pedalling speed, but the force is greater; with a smaller number of teeth, the speed as well as the force are smaller. On racing bicycles presently on the market, a smaller size sprocket is added to the command sprocket where the number of teeth can be varied to give the bicycle greater or less speed, and greater or less force, according to the needs of the cyclist. This is the conventional structure as found on the market up to the present time.